1. Field of the Invention
This invention disclosed an electronically controlled heating device, this used device to form a region of constant high temperature on one side of the insulating material, and causes most of the heat transfer to concentrate in a longitudinal heat flux, which flows across the direction of the thickness of object-to-be-tested, to achieve the effect of one-dimensional heat transfer.
2. Background of the Invention
Insulation technique may be applied with improved quality, manufacturing process, or structure of the insulating material. Whether it is the improvement in the quality of existing insulating material, or evaluating the on-site insulating proficiency as the basis of improvement, the testing of the insulating effectiveness remains a necessity.
In general, testing of insulating effectiveness is limited within the laboratory, and requires the use of test pieces for measurement. Direct application on the entire product is not possible. For testing of insulating effectiveness on compound materials, especially the testing of a vacuum insulating layer or an on-site insulating layer, it is even more impossible to cut off the insulating layer and make them into test pieces to be placed into a traditional heat-flow gauge/insulation measuring apparatus for testing.
Currently, an apparatus which may be used for measuring on-site heat insulation is Japan's QTM (Quick Testing Method). It estimates the k value from temperature changes on the surface of the insulating material but may only be used on objects which are thicker and are made of a homogeneous material. Therefore, it is primarily used on construction materials such as cement wall. Generally, testing of insulating materials is limited within the laboratory and requires the use of test pieces for measurement, and may not actually be conducted on the product itself.
A similar insulation measuring apparatus is reported by R. E. Collins, et al, in 1992 and published in Transparent Evacuated Insulation (Solar Energy), Volume 49, 3rd issue, pp. 333-350. It utilizes hot water (21) and cold water (22) to maintain constant temperatures on two sides. In the middle region above them, there is an electric temperature-control device (23) which is maintained at the same temperature with that of the upstream hot water (21), and the coefficient of the heat transfer point is calculated from the temperature difference between the top and the bottom, and the electro-calorific value. Its defects are: a) water which is used as a medium for heat control needs to be maintained at a certain temperature; Collins insulation measuring apparatus has a complex structure and enormous size; b) it can only test the test pieces and cannot test the actual object.
Problems Which the Invention Intends to Resolve
In view of past methods for evaluating insulating effectiveness of materials or on-site insulating effectiveness, this invention can utilize a non-destructive approach to measure the insulating effectiveness of frozen/air-conditioned products, and can be used for quality inspection of the insulating effectiveness of products.
This invention has been designed as a portable and stabilized prototype insulating effectiveness measuring apparatus, which has a portable feature, and is suitable for use in measuring the insulating effectiveness of frozen/air-conditioned products. Not only is it beneficial for random product inspection and research for energy conservation, it also compensates the defects of the Quick Testing Method.
One other critical feature of this invention is its utilization of the theory of zero heat transfer in a region with uniform temperature to cause heat to flow in a single direction, thus leading to the design of an electrically controlled heating device.